Since the discovery of ferrocene in 1951, a number of metallocenes have been prepared by the combination of anions having the cyclopentadienyl structure with various transition metals. The term "cyclopentadienyl structure" as used herein refers to the following structure. ##STR1## Such "cyclopentadienyl structure" can be formed by addition of various metal alkyls to cyclopentadiene and "cyclopentadiene-type" compounds.
The term "cyclopentadiene-type compound" as used herein refers to compounds containing the cyclopentadiene structure. Examples of cyclopentadiene-type compounds include unsubstituted cyclopentadiene, unsubstituted indene, unsubstituted tetrahydroindene, unsubstituted fluorene, and substituted varieties of such compounds.
Many of the cyclopentadiene-type metallocenes have been found useful in catalyst systems for the polymerization of olefins. It has been noted in the art that variations in the chemical structure of such cyclopentadienyl-type metallocenes can have significant effects upon the suitability of the metallocene as a polymerization catalyst. For example, the size and substitutions on cyclopentadienyl-type ligands have been found to affect the activity of the catalyst, the stereoselectivity of the catalyst, the stability of the catalyst, and other properties of the resulting polymer; however, the effects of various substituents is still largely an empirical matter, that is, experiments must be conducted in order to determine just what effect a particular variation will have upon a particular type of cyclopentadienyl-type metallocene. Some examples of some cyclopentadienyl-type metallocenes are disclosed in U.S. Pat. Nos. 4,530,914; 4,808,561; and 4,892,851, the disclosures of which are incorporated herein by reference.
In the past most polymerization work has been done using homogeneous, i.e. soluble, metallocenes rather than heterogeneous systems in which the metallocene is insoluble during the polymerization. However, for many industrial applications it would be desirable to have insoluble supported forms of metallocenes that are still active as polymerization catalysts.
It is also envisioned that such heterogeneous catalysts would have other uses. For example, the compositions could possibly be used as catalysts for hydrogenation, alkene epoxidation, alkene isomerization, ketone reduction, stereoselective alkene polymerization, and as reagent for stereoselective cobalt-mediated reactions, alkyltitanium addition reactions with aldehydes, and formation of allylic amines.
Accordingly, an object of the present invention is to provide methods for producing such heterogeneous catalysts. Still another object is to provide novel organic compounds suitable for use in preparing metallocenes.
An object of the present invention is thus to provide certain new organic compounds, including bridged ligands and metallocenes. Another object of the present invention is to provide a method for preparing new organic compounds including bridged ligands and metallocenes. A further object of the present invention is to provide supported, bridged ligands and metallocenes. Yet a further object of the present invention is to provide a process for preparing the supported, bridged ligands and metallocenes. Still another object of the present invention is to provide polymerization catalysts employing the supported metallocenes. Yet another object of the present invention s to provide processes for the polymerization of olefins using the supported metallocene catalyst systems. Still yet another object of the present invention is to provide polymers produced using such supported, metallocene catalysts.